If you already had sales order delivered then Credit&Rebill is the correct option.
In standard SAP when a sales order is created the customer master data is copied into the sales order.
You can change the custom master that those changes no longer will affect an existing sales order. This is done to preserve integrity of the data for legal and audit reason. Until the delivery is done you can still go into the sales order itself and change the sold-to/ ship-to/ bill-to partner addresses directly bon the partner tab. But once the delivery is done pretty much of the sales order information is locked, you can no longer make changes.